DTHY 186: Mandibular Incisors

Review: Basic components of tooth

Review: Basic components of tooth Cont.

Primary Pulp

Pulp is larger

Permanent Pulp

Less pulp and more dentin

Clinical application: Pulp exposure

Radiographic View of Pulp, Pulp chamber, and pulp horn

Incisor Pulp

Dividing the CROWN into THIRDS

- Incisal 1/3

- Middle 1/3

- Cervical 1/3

Incisor functions

1. Cut food

2. Articulation of speech

3. Help with lip support: Appearance

4. Guid the mandible posteriorly during the final phase of closing before the posterior teeth contact: Guides incisal edges of mand. to fir against the lingual surfaces of the max. incisors

Incisor class traits

- All ant. teeth form 4 LOBES: 3 Facial and 1 Lingual

Facial aspect of incisors

- Developmental grooves divide the lobes and are sometimes evident on newly developed teeth.

- Mamelons = 3 lobes on incisal edge

Lingual aspects of incisors

4th lobe forms bulge near gingival margin called CINGULUM

Incisor classic traits cont.

Another view of the incisor

Crowns taper from the incisal 1/3 to the cervical 1/3

Proximal Contacts for Mandibular Incisors

Superior view of Proximal Contacts

Categories of Mandibular Incisors

Central and Lateral incisors

Mandibular central incisors

- #24 and #25

- Eruption time = 6 to 7 years

- Root formation = 9 years

- Occludes with max. central incisors

Midline is between...

...#24 and #25

Succedaneous Teeth

Permanent teeth that replace the deciduous teeth.

Mandibular Central Incisor: Incisal View

- Crown wider Mesial to Distal (mesiodistally)

- Incisal ridges ridge straight Facial to Lingual

Mandibular Central Incisal View Features

- Centered CINGULUM= 4th lobe

- Mesial to Facial of contour centered

Mandibular Central Incisor: Facial View

- Narrowest Mesial to distal (mesiodistally) of all incisors

- Shortest tooth in dentition

- Bilaterally symmetrical

- M and D profiles of tooth taper evenly from incisal edge to apex

Mandibular Central Incisor: Facial View Cont.

- M, I, and D 90 degree angle

- M and D HOC in incisal third at same level

- Developmental depressions faint or absent

Mamelons

Wear Facets

Wear if the incisal edge

Mandibular Central Incisor: Lingual View

- Lingual surface is very smooth

- Marginal ridge= Lingual to distal

- Cingulum= 4th lobe

- L fossa= Depression of backside of tooth

Mandibular Central Incisors have a centered...

...Cingulum

Mandibular Central Incisors: Mesial View

- Facial margin straight line from height of contour to incisal

- Lingual edge convex (sticks out) at cingulum, concave (scoops in) up to incisal ridge, and convex (sticks out) at incisal ridge

- CEJ more curved

Mandibular Central Incisor: Mesial View cont

- F and L root parallel cervical half (top) and narrow at apex

- Root surface is broad and flat with longitudinal depression (calc. collects here)

- Insisal ridge is slightly lingual to axis of the root

Mandibular Central Incisor: Distal View

- CEJ is less curved than mesial

- Typically covered by gingiva/periodontium

- Root depression slightly deeper than mesial

Mandibular central incisor mesial and distal views compaired

Mandibular lateral incisor

- #23 and #26

- Eruption time= 7 to 8 years

- Root completion= 10 years

- Occludes with max central and lateral

Mandibular lateral incisor: Incisal View

- Appears twisted

- D more lingual than M

- "Distolingual twist"

Distolingual twist

Distal incisal edge is more lingual and tilts lingually

- Cingulum is OFF centered

Mandibular Lateral Incisor: Facial View

- Crown slightly wider mesiodistally than mandibular central crown

- Root longer than mand. central; total tooth approx. 2mm longer

- M incisal angle sharp, nearly right angle

- D side of insisal angle rounded

Mandibular Lateral Incisor: Facial View cont.

- M profile of crown is nearly straight

- D crown profile is more convex (sticks out)

- D HOC more cervical than M HOC

- Root is wider facioingually than mesiodistally

Mandibular Lateral Incisor: Lingual View

Similar to mand. cen. incisor except differenced noted in facial view

Mandibular Lateral Incisor: Mesial View

- Similar to mand. cen. except distal mesial ridge may be visible in background (tooth less straight than cen. incisor)

- Mesial CEJ more curved

Mandibular Lateral Incisor: Distal View

- Distal CEJ less curved than mesial

- Distal root depression deeper than mesial